In the area of "double explanations" I have the student construct a
device that will project a projectile at least 5 meters and is capable
of being tilted at 5 degree steps. We speed about 2 days firing the
devices and measuring the range. They then graph the data to find the
optimum angle for maximum range.
Then we go into the classroom and work on "deriving" the range equation.
Those students who are in the Calculus are then given the opportunity to
show the class how to find the maximum of the function.
It's a good example of the tie between experimental and theoretical
physics. Plus the students like building stuff and then being able to go
outside and test their theory.